Residential and commercial building construction uses a variety of building materials and construction techniques to complete the structure. In some building projects, lumber or metal studs are used for the framing. The frame structure is held together with nails, screws, and bolts. An exterior siding such as stucco, wood, vinyl, brick, or aluminum is placed over the frame structure. Insulation is placed between the studs of the frame structure. The interior coverings such as drywall are affixed to the inside of the frame structure. The entire building project is typically performed on the construction site. The use of interior and exterior siding over frame is costly and labor and time intensive. Wood framing is of inferior quality and subject to insect damage and warping. Metal framing is thermally conductive which is undesirable in view of energy costs. The frame-based structure is susceptible to the effects of aging and storm damage. While frame construction has been dominant in the building industry for many years, other more cost effective and time efficient solutions are becoming more common.
One alternative building approach involves the use of hollow sectional forms, which are put together in the shape of the exterior wall. The hollow forms are filled with concrete and then disassembled when the concrete sets, leaving a concrete wall. The concrete wall is long-lasting and strong against the elements, but the forms are generally expensive to setup.
Another building approach involves the use of pre-fabricated building panels which are manufactured off-site and then assembled together on-site. One such building panel is discussed in U.S. Pat. No. 6,796,093 as having a plurality of I-beam-shaped metal struts spaced about 18 inches apart with insulating foam blocks disposed between the metal struts. The metal struts have cut-outs along the length of the I-beam to reduce the total metal area and associated thermal conductivity. FIG. 1 shows exemplary prior art I-beam metal strut 12 between foam blocks 14. While the structural panel has good load-bearing characteristics, the I-beam metal strut 12 is continuous across foam block 14, at least through portions of the metal struts and, consequently, is thermally conductive through the continuous metal areas. Since I-beams 12 go completely through foam blocks 14, heat and cold will conduct from one side to the other side of the wall structure. In the summer, I-beam 12 conducts heat from the exterior to the interior of the building. In the winter, I-beam 12 conducts cold from the exterior to the interior of the building. In any case, the I-beam construction decreases the thermal insulation property of the building panels.
A need exists for building panels combining strength with thermal insulating efficiency.